Truss table with integrated positioning stops

ABSTRACT

A table for forming trusses comprises a support frame and first and second substantially horizontally-disposed elongate panels wherein each of the panels has an upper surface, a lower surface, and opposing lateral edge portions with a gap being formed between the panels. A first channel is also included and has a generally horizontal floor and opposed side walls extending upwardly therefrom. One of the side walls supports the lower surface of the first panel, and the other of the side walls supports the second panel. The floor is supported by the frame and is positioned beneath the gap. The table also includes magnetic positioning indicia mechanism located within the channel and magnetically attached to the first channel floor.

RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application Ser.No. 60/006,169, entitled TRUSS TABLE WITH INTEGRATED POSITIONING STOPS,filed 2 Nov. 1995.

FIELD OF THE INVENTION

This invention relates generally to truss tables, and more particularlyrelates to truss tables having integrated positioning stops.

BACKGROUND OF THE INVENTION

Trusses for the roof and floor of a dwelling typically comprise a seriesof lumber planks arranged in a triangulated pattern. Truss design variesfrom house to house because of consumer demand for individualized homedesign, but within a single home generally several trusses of identicalconfiguration will be employed.

A particularly time-consuming task of truss construction is the "set-up"process, which is the placement of locator stops on a truss table intopositions in which they force truss planks into the proper position andorientation for subsequent attachment. Each set of planks is precut tothe proper length and end angle, but must be arranged on a truss tablein the correct triangulated truss configuration prior to being fixedinto that configuration with truss plates.

Because set-up can be so time consuming, generally a set-up system isused to hasten the set-up process. A set-up system typically includes anumber of locator stops, or "jigs", which are positioned on the trusstable in a pattern that defines the proper placement of planks on thetable. These jigs are typically disk-shaped and include some means forsecuring themselves to the truss table. The positions of the jigs areusually predetermined for the truss manually or by a software programassociated with the set-up system, such as the FREEFORM program offeredby Trenco Engineering, Edenton, N.C. The planks are then arranged on thetable, with their positions and relative orientations being defined bythe positions of the set-up jigs. Other locator stops and fixtures,which can take the form of additional disks or flat surfaces that abutportions of a plank, are then placed around the planks based on thelocation of the planks and secured to the truss table.

Once the locator stops and fixtures are properly positioned, the planksare attached to one another by a pressure roller or hydraulic presswhich presses a connecting truss plate into adjoining planks to form thetruss. The completed truss is removed from the table, and another set ofplanks is guided into position within the locator stops and fixtures.The locator stops remain in place until all trusses of the selectedconfiguration have been formed. They are then removed, and the set-upjigs, locator stops, and fixtures are once again positioned on andsecured to the table to define the configuration for the next trussconfiguration.

Set-up systems with positioning capability have been offered in avariety of configurations. For example, U.S. Pat. No. 5,085,414 toWeaver discloses a jig for forming trusses which includes a blockdesigned to fit within the rails of a C-shaped channel that extendsalong the length of the surface of a truss table. The C-shaped channel,which is recessed within adjacent panels of the table, includesinwardly-directed lips that capture the aforementioned block. Adisk-shaped stop is connected with the block by a threaded clampingbolt. The jig can be moved along the length of the C-channel and fixedat a predetermined location in which the stop can define a portion ofthe truss. A measuring scale fits atop and extends along the length ofone of the C-channel rails, and a pointer extends from the block towardthe scale to provide the operator with a reference point for positioningthe jig during set-up.

Another exemplary set-up jig configuration is shown in U.S. Pat. No.4,493,038 to Harnden. This truss assembly apparatus includes a jigpositioned upon a worm gear located within a C-channel. Rotation of theworm gear causes the jig to translate within the C-channel to thedesired predetermined location for set-up.

Each of these C-channel-based set-up jig configurations requires thatthe C-channel be positioned below the table surface so that the top lipsof the C-channel are level with the table surface. Although thisconfiguration is suitable for truss tables with wooden table surfaces,it is not particularly suitable for the newer, more preferredsteel-topped tables. The table surface of a steel-topped table has arelatively thin depth profile (compared to wooden table surfaces) andpreferably is provided to the operator as a single slab; this canpreclude the recessing of a C-channel therein.

Another significant shortcoming of these jigging systems is that the toplips of the C-channel of Weaver and the teeth of the worm gear ofHarnden are prone to deflect permanently when under stress. Such stressoften results when slightly warped planks are bent and forced into placeafter the set-up jigs are positioned. The forces exerted on the stops ofthe jigs by the deflected planks can easily be of sufficient magnitudeto cause the lips of the C-channel to deform permanently. Thedeformation can be significant enough that the jig contained therein canno longer move freely within the C-channel, and thus is no longerusable. Deformation of the C-channel lips is particularly likely whenthe set-up jigs are used for both set-up and manufacturing processes. Asa result, the C-channel-based jigging systems are only suitable for theset-up process and should not be used as semi-permanent locator stops.

Another set-up jig design suggested for use with steel-topped tables isillustrated in U.S. Pat. No. 5,385,339 to Williams. The Williams set-upjig is a steel block having a recess on its lower surface that mateswith a thin metal ruler that extends across the length of the trusstable. The steel block slides upon the ruler and is fixed into apredetermined position by a bolt inserted through a laterally positionedaperture in the block and into one of the grid holes of the truss table.The most serious shortcoming of this jigging system is thesusceptibility of the ruler to become bent along its edges by contactwith truss planks; once this occurs, the steel block no longer slidessmoothly on the ruler. Also, this system is intended to be used forset-up alone and not actual truss manufacture.

One steel-topped table that addresses some of these shortcomings isdescribed in co-pending and co-assigned U.S. patent application Ser. No.08/552,283 to Williams, entitled TRUSS TABLE WITH INTEGRATED POSITIONINGSTOPS ("the Williams Application"), the disclosure of which is herebyincorporated herein in its entirety. The truss table disclosed thereinincludes a plurality of steel panels positioned to have gaps betweentheir side edges. Locator stops are positioned within the gaps and canbe clamped directly to the side edges of adjacent panels, which are farstronger and more rigid than the lips of the C-channel employed in priorart tables.

Another difficulty faced by truss manufacturers is the alignment ofadjacent truss tables. Truss tables are typically constructed withrelatively few C-channel rails (perhaps 6 to 8 per table) spaced atintervals of about 6 to 10 inches. Of course, a typical truss (e.g., onethat is 45 feet in length) cannot fit onto a single table of this size.As a result, truss manufacturers employ several truss tables positionedside-by-side to support the entire truss. The employment of multipletables that include some type of positioning system supported by a trussengineering software program, such as that of Weaver, Harnden, orWilliams, requires that each of the tables be precisely aligned orregistered with the remaining tables in order for the positioning systemto be useful; otherwise, the positioning system will indicate a positionfor the locator stops of some tables that is longitudinally offset fromproper alignment. Because truss tables can be quite heavy, it issomewhat difficult to position them precisely. Also, it may not beapparent to the operator if the tables become misaligned during repeatedoperations.

It has been suggested that, instead of shifting the tables to theirproper positions, a laser image of the truss be projected onto the tablesurfaces. See U.S. Pat. No. 5,383,318 to Petta. The use of an overheadimaging system eliminates the need for precise table positioning.However, these systems are quite expensive, and therefore are notpractical for many truss manufacturers. In addition, the laser image isoften difficult to discern unless the truss manufacturing facility iskept quite dark, a working condition that can be difficult or evendangerous. These deficiencies render imaging systems inadequate for manymanufacturers.

One solution to this problem offered in the Williams Application is theuse of a scale that can be adjusted longitudinally within the gapbetween adjacent panels. The adjustability of the scales of adjacenttables enables the scales to be registered, therefore ensuring accuratepositioning of locator stops, even on adjacent tables. However, thissolution is somewhat costly; the scales disclosed include slots on eachend that receive tightening bolts. Of course, inclusion of these slotsincreases the cost of the scales.

An additional shortcoming of prior truss tables emerges when one or moreof the truss planks is somewhat bowed or warped. As noted above, afterthe set-up process is complete, semi-permanent fixtures are placedaround the truss planks to press on the planks and thereby "tighten" thejoints of the truss. These fixtures are positioned, oriented and securedto the truss table based on the shape of the truss planks used forset-up. If some planks used either for set-up or in a subsequent trussare bowed or warped, the placement of the fixtures and locator stops mayrender placement of the later-used planks within the pattern defined bythe fixtures and stops difficult, if not impossible. In addition, oftenduring the pressing operation pressure applied to one end of a warpedplank forces the opposite end of the plank to rise and become dislodgedfrom its position within the locator stops and fixtures. Once dislodged,the plank is no longer restrained in a position within the desiredpattern. When the pressure roller reaches the dislodged end, it isunable to force that end into the pattern due to the shift in positionof the plank. The prior art is silent on methods of correcting thisproblem.

A further technical issue raised by prior art truss tables is the use of"intermediate" locator stops (i.e., locator stops positioned atlocations other than below the bottom chord and above the top chord ofthe truss). These locator stops are used selectively, and therefore arenot included in all channels of the tables. However, prior art designsrender their use somewhat inconvenient, as the block of the locator stopreceived within the channel is of sufficient size that it can bridge thegap above the channel in order to prevent the locator stop from slippingout of the channel through the gap. As a result, the block must beinserted at the longitudinal end of the channel. This, of course,requires removal of at least one non-intermediate locator stop prior toinsertion of the intermediate stop, followed by the re-insertion of thenon-intermediate locator stop. Also, the intermediate stops must beinserted before the planks are arranged so that they can be positionedon the interior of the planks. Accordingly, the operator must anticipatewhen such stops are to be used prior to the arrangement of the planks.This inconvenience can render the use of intermediate locator stopsinefficient.

Still another technical issue raised by prior art truss tables is howtrusses are ejected after construction. Prior art tables typicallyinclude a mechanism that retracts within a central channel in the tableduring construction and extends above the channel once construction iscomplete to eject the truss. The mechanism can be designed to ejecttrusses off the end of the table (such that the trusses travel in adirection perpendicular to the channel in the truss table) or off theside of the table (such that the trusses travel in a direction parallelto the channel in the truss table). Side-eject tables typical includesmall wheels that rotate about horizontal axes perpendicular to thetable channel and thereby roll trusses toward and off the side of thetable. End-eject mechanisms typically include a long cylinder disposedparallel to the table channels that rotates about a horizontal axisparallel to the channels. End-eject mechanisms are particularly usefulwhen used in conjunction with a lifting mechanism located at the end ofthe endmost truss table, such as that described in U.S. Pat. No.5,553,375 to Powers, the disclosure of which is hereby incorporatedherein by reference in its entirety. A truss construction firm typicallyorders a truss table having whichever of these ejection mechanisms bestfill the needs of the factory. A truss table containing the desiredmechanism is then built and shipped. Clearly, it would be desirable fortruss table suppliers to have a single configuration that can be used toeject trusses to the side or end of the truss table.

In view of the foregoing, it is an object of the present invention toprovide a truss plank positioning system suitable for use with steelpanel-style truss tables, including both intermediate andnon-intermediate locator stops.

It is also an object of the present invention to provide an intermediatelocator stop that overcomes the inefficiency of those found in the priorart.

It is another object of the present invention to provide a truss tablewith an inexpensive positioning system that can be easily and preciselyaligned and registered with adjacent truss tables.

It is an additional object of the present invention to provide anapparatus for adapting the locator stops of a truss table to account forwarpage and bowing in truss planks.

It is a further object of the present invention to provide a truss tablethat can eject a truss off either its end or its side.

SUMMARY OF THE INVENTION

These and other objects are satisfied by the present invention, whichprovides an improved truss table and fixtures therefor. As a firstaspect, the truss table of the present invention comprises a supportframe, first and second substantially horizontally-disposed elongatepanels, a first channel having a generally horizontal floor and opposedside walls extending upwardly therefrom, and positioning indicia meanslocated within the channel. Each of the panels has an upper surface, alower surface, and opposing lateral edge portions. The panels arepositioned so that their respective upper surfaces are substantiallycoplanar and so that a first of the lateral edge portions of the firstpanel is in adjacent, non-contacting relationship with a first of thelateral edge portions of the second panel to form a gap therebetween.The channel is configured such that one of the side walls supports thelower surface of the first panel, and the other of the side wallssupports the second panel. The floor of the channel is supported by theframe and positioned beneath the gap so that the first lateral edgeportion of the first panel and the first lateral edge portion of thesecond panel overhang the floor. The floor is formed of a ferromagneticmaterial. The positioning indicia means is magnetic and magneticallyattached to the first channel floor. With this configuration, the trusstable can be quickly and easily registered to other tables by adjustingthe position of the positioning indicia means, thereby forming a precisegrid for positioning locator stops.

As a second aspect, the present invention includes a locator stop foruse with a truss table that includes an upper surface, at least oneelongate gap therein, and a lower surface. The locator stop comprises astop portion that resides above the truss table upper surface, a captureportion that resides below the gap, and means for clamping the trusstable upper and lower surfaces between the stop portion and captureportion. The clamping means extends within the gap. The stop portionincludes a generally flat and generally horizontally-disposed uppersurface, generally upright side walls beneath said upper surface, and abevelled surface disposed between and merging with the upper surface andthe side walls. The bevelled surface assists in the positioning of bowedor warped truss planks during the placement thereof and also aids warpedtruss planks that slip out of position during pressure rolling.

As another aspect, the present invention includes a locator stop thatcan be inserted into a channel in a truss table from above. The locatorstop comprises a stop portion that resides above the truss table uppersurface, a capture portion that resides below the gap, and means forclamping the edges of the truss table between the stop portion and thecapture portion that extends within the truss table gap. The captureportion is configured such that, in a first rotative orientation, thecapture portion bridges each of the truss table edge portions fromunderneath, and in a second rotative orientation, the capture portioncontacts neither of the truss table edge portions. This configurationenables the capture portion to be lifted through and removed from thetruss table gap.

It is preferred that, with such a locator stop, the clamping means be abolt having a hexagonal head and an attached collar. This configurationrenders the clamping procedure quick and simple with readily availabletools.

As an additional aspect, the present invention includes a truss tablehaving means for ejecting a completed truss from its constructionsurface. The ejecting means includes a lifting unit and means forrolling constructed trusses away from the construction surface. Thelifting unit is connected to the frame of the truss table and to therolling means. The lifting unit is configured to move the rolling meansbetween a retracted position within a recessed channel in theconstruction surface, wherein the rolling means is positioned below theconstruction surface, and an extended position, wherein the rollingmeans is positioned above the construction surface. The rolling means isconfigured so that constructed trusses are free to roll in anyhorizontal direction. Preferably, the rolling means comprises aplurality of ball bearings that are mounted on a mounting rail forunimpeded rotation. This configuration enables the operator to eject thetruss from either the end or the side of the truss table.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a plan view of seven truss tables of the present inventionillustrating how they can be used in combination to form a single truss.

FIG. 2 is a plan view of a single table of the present invention.

FIG. 3 is an enlarged perspective cutaway view of the truss table ofFIG. 2 showing the relationship between the components of a primarylocator stop, a channel and a magnetic scale.

FIG. 4 is an enlarged cutaway plan view of the table of FIG. 2 showingone primary locator stop positioned within a channel.

FIG. 5 is a sectional view taken along lines 5--5 of FIG. 4 showing aprimary locator stop in a clamped position.

FIG. 6 is an exploded perspective view of a secondary locator stop.

FIG. 7 is a partial view of a truss defined with primary and secondarylocator stops and with both non-angled and angled fixtures.

FIG. 8 is an exploded view of a secondary locator stop and a positioningfixture.

FIG. 9 is an exploded view of the positioning fixture of FIG. 8 with itsbearing insert removed.

FIG. 10 is a perspective view of the fixture of FIG. 8 showing how asecondary locator stop can be positioned therein.

FIG. 11 is a bottom section view of the secondary locator stop of FIG.10 with its rotary T-nut shown in its clamped and unclamped positions.

FIG. 12 is a side section view of the secondary locator stop of FIG. 11in its clamped position.

FIG. 13 is an enlarged view of an angled fixture clamped into placeabutting adjoining truss planks.

FIG. 14 is an enlarged side section view showing the ejector rail in itsretracted position.

FIG. 15 is an enlarged side section view of a truss table showing theejector rail in its extended position.

FIG. 15A is a side section view of an alternative embodiment of alifting mechanism shown in the extended position.

FIG. 16 is an enlarged partial plan view of a truss table with itsejector rail in the extended position illustrating how a constructedtruss can be ejected in any direction.

FIG. 17 is a greatly enlarged partial section view of a ball bearingmounted in its mounting shell.

FIG. 18 is a partial plan view of another alternative embodiment of alifting mechanism shown in the extended position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described more particularlyhereinafter with reference to the accompanying drawings, in whichpresent embodiments of the invention are shown. The invention may,however, be embodied in many different forms and is not limited to theembodiments set forth herein; rather, these embodiments are provided sothat the disclosure will fully convey the scope of the invention tothose skilled in the art.

Referring now to the drawings, seven truss tables 20 upon which a truss22 has been constructed are illustrated in FIG. 1. The truss 22comprises a number of wooden planks 23 which are arranged in atriangulated web. The planks 23 are interconnected with one another bytruss plates 25, the configuration of which can be any of those known tothose skilled in this art to be suitable for interconnecting woodenplanks. It should be understood that, although seven truss tables 20 areillustrated herein, any number of truss tables can be employed togetherto construct a larger or smaller truss than that illustrated.

Referring now to FIG. 2, a single truss table 20 is illustrated. Thetruss table 20 comprises ten horizontally disposed steel panels 50, eachof which is approximately 6 inches in width and 0.75 inches in depth(best seen in FIG. 3). Those skilled in this art will recognize that thepanels 50 can be of any desired width (e.g., 2 inches, 4 inches, 8inches, 12 inches, or the like) or depth (e.g., 1/2 inch, 1 inch, or thelike) that can withstand the rigors of truss construction, andindividual panels 50 can be of equal or differing width as desired. Thepanels 50 can be of any length sufficient to support a truss beingconstructed thereon.

Still referring to FIGS. 2 and 3, the panels 50 are elongate and areoriented to be substantially parallel to one another. Opposed lateraledge portions 56 of adjacent panels 50 are in non-contacting adjacentrelationship to the lateral edge portions 56 of adjacent panels 50,thereby forming gaps 58 therebetween. Each gap 58 is typically betweenabout 1/4 and 1 inch or greater in width and is preferably about 3/4 ofan inch. The upper surfaces 52 of the panels 50 support the planks 23 ofeach truss 22 that is constructed on the table 20.

Referring again to FIG. 2, the truss table 20 also includes primary andsecondary locator stops 60, 80 that are positioned above and within thegaps 58 between adjacent panels 50. The locator stops 60, 80 help todefine the triangulated pattern of the truss 22 and thus aid inplacement and retain the truss planks 23 in position prior to and duringthe construction of a truss. Illustratively, two primary locator stops60 are included in each of two gaps 58, and between zero and threesecondary locator stops 80 are included in each gap 58. The truss table20 also includes a centrally-located, longitudinally-extending ejectorunit 140 located in a central channel 28 for ejecting trusses afterconstruction is complete.

Referring back to FIG. 1, a pair of semipermanent fixtures 100 areincluded on two truss tables 20. Also, a pair of compound fixtures 120are included with a single truss table 20. The fixtures 100, 120 alsoaid in placement and retention of truss planks before and during trussconstruction.

Referring now to FIG. 3, each pair of adjacent panels 50 is supported onits lower surface 54 by a longitudinally-extending channel 30, which issupported by a frame 24. Those skilled in this art will recognize that,although only one channel 30 is described in detail herein, thisdescription is equally applicable to the other channels 30 of theillustrated truss table 20.

The channel 30 comprises a horizontally disposed floor 32 having anupper surface 34 and a pair of opposed, generally vertically disposedsidewalls 36a, 36b. The lower surface of the floor 32 is welded to theframe 24. The respective upper ends 38a, 38b of the sidewalls 36a, 36bare welded to the lower surface 54 of adjacent panels 50. The panels 50are positioned relative to the sidewall upper ends 38a, 38b so thattheir adjacent lateral edge portions 56 overhang a portion of the floor32, and the gap 58 between adjacent lateral edge portions 56 is abovethe floor 32. In this configuration, the channel 30 can capture, retain,and provide a sliding path for a sliding portion of the primary locatorstops 60 and the secondary locator stops 80.

The channel 30 can be constructed from a single unitary component, suchas the channel iron illustrated herein, or can be formed of two or morepieces attached to form a channel. Preferably, the channel 30 is betweenabout 1/4 and 5 inches in height (i.e., the distance between the panellower surfaces 54 and the channel floor upper surface 34) and betweenabout 3/8 and 10 inches in width (i.e., the distance between facingsurfaces of the side walls 36a, 36b). It is preferred that the floor 32be formed of a ferromagnetic material (defined herein as a material towhich a magnetic component will adhere).

As used herein, it is intended that the term "channel" also encompass analternative embodiment in which the frame 24 or other underlyingstructure forms the channel floor 32. In particular, it is envisionedthat the panels and channels of the truss tables of the presentinvention can be formed upon an existing steel=topped or wood-toppedtable as described in the Williams application referenced above.

Still referring to FIG. 3, a magnetic measuring scale 40 rests upon thechannel floor upper surface 34. The measuring scale 40, which extendslongitudinally within the channel 30, includes positioning indicia 42 onits upper surface 41. The scales lower surface 44 contacts and overliesthe channel floor 32. Preferably, the lower surface 44 is magnetizedsuch that it will adhere to the ferromagnetic floor 32 and therebysecure the scale 40 thereto. Because the scale 40 is secured throughmagnetic attraction to the floor 32, it can be adjusted easily to alignwith other scales 40 on other tables 20.

Referring now to FIGS. 3 through 5, the primary locator stop 60illustrated therein includes an annular stop disk 61, a slide block 75,a bolt 65, and a nut 71. The stop disk 61, which includes an uppersurface 62 and a circumferential side wall 69, rests upon the uppersurfaces 52 of adjacent panels 50. The upper surface 62 of the disk 61and the side wall 69 merge into a circumferential beveled surface 63.The disk 61 also includes a centrally located recess 64 and an aperture70 extending downwardly therefrom. Although the annular configuration ofthe stop disk 61 is preferred for its uniformity of contact with trussplanks irrespective of their relative orientation, those skilled in thisart will recognize that any means for defining a pattern of truss planksand for preventing movement of an abutting truss plank can be used withthe present invention.

The bolt 65 includes a hexagonal head 66, a collar 67 that underlies andextends circumferentially away from the head 66, and a threaded shank68. The bolt 65 extends through the recess 64 and the aperture 70 of thedisk 61 and through the gap 58 between the adjacent panels 50. The shank68 then is received within a threaded aperture in the nut 71, whichincludes a body 72, two wings 73 extending in opposite horizontaldirections from the body 72, and a projection 74. The projection 74protrudes from the lower surface of the body 72 and is received within arecess 76 of the slide block 75 (see FIGS. 3 and 5). The slide block 75,which is preferably formed of a transparent material, such aspolycarbonate, also includes a bevel 77 at its forward end and asighting edge 78. The slide block 75 is positioned within the channel 30to slide upon the scale 40.

Those skilled in this art will appreciate that, although the primarylocator stop 60 illustrated herein is preferred, other locator stopconfigurations can also be used with the present invention. The primarylocator stop selected should include a stop portion (such as the disk61) for assisting in the positioning of a truss plank pattern andretaining truss planks in that pattern during manufacture, a slidingportion (such as the slide block 75) that enables the locator stop tomove within the channel 30, and clamping means (such as the bolt 65)that clamps the lateral edge portions 56 of adjacent panels 50 betweenthe stop portion and the sliding portion and thereby retains the primarylocator stop 60 at the location in which it is clamped. An exemplaryalternative positioning stop is illustrated in the Williams application.It is intended that the present invention encompass configurations inwhich the stop and slide portions directly contact the panel upper andlower surfaces and those in which there is some structure, such as ashim or overhanging channel lip, between the stop or slide portions andthe table panels.

Referring now to FIGS. 6, 11 and 12, an exemplary secondary locator stop80 is illustrated. The secondary locator stop 80 includes a disk 81, abolt 85, and a rotary T-nut 91. The disk 81 has the same configurationas the disk 61 described hereinabove; i.e., it includes an upper surface82 and a sidewall 89 that merge into a bevelled surface 83, and furtherincludes a recess 84 in the upper surface 82 leading to an aperture 90.Similarly, the bolt 85 has the same configuration as the bolt 65described hereinabove; it has an hexagonal head 86, a collar 87 and athreaded shank 88. The rotary T-nut 91 includes a parallelogramatic body92 having therein an aperture 93 and wings 94 extending from oppositesides of the body 92. The body 92 includes opposed sidewalls 95a, 95bwhich are continuous with the side edges of the wings 94; the body 92also includes opposed side walls 96a, 96b which are angled relative tothe sidewalls of the wings 94. The body 92 and wings 94 are sized suchthat, in a first rotated position, the nut 91 can be slipped into orlifted through one of the gaps 58; however, in a second rotatedposition, the body 92 can fit within the gap 58, but the wings 94 bridgethe gap 58 from underneath. This configuration allows the nut 91 to beinserted into a channel 30 through a gap 58 from above, then rotatedwith the body 92 within the gap 58 so that the bolt 85 can be used toclamp two adjacent panels 50 between the disk 81 and the nut 91 (seeFIGS. 11 and 12).

Turning now to FIGS. 7 through 12, the semi-permanent fixture 100illustrated therein includes a pair of capture rails 102, each of whichhas a horizontally disposed inner panel 103, and a cross-member 104. Theinner panels 103 and the cross-member 104 define therein an open-endedslot 105. A bearing insert 106 can be inserted onto the cross-member 104to provide an additional bearing surface if so required; the bearinginsert 106, which includes a bevelled surface 107, is removably securedto the cross-member 104 with two interference fit pins 109.

As illustrated in FIGS. 7, 8, and 10 through 12, the semi-permanentfixture 100 is secured to the truss table 20 via a secondary locatorstop 108. The secondary locator stop 108 can be inserted into the openend of the slot 105, then tightened as described above to clamp thefixture 100 into position.

Referring now to FIGS. 7 and 13, an angled fixture 120 is shown. Theangled fixture 120 includes two fixture halves 122a, 122b, each of whichhas slots 123 therein. The fixture halves 122a, 122b are configured verymuch like the semi-permanent fixture 100 with open-ended slots 125included therein. However, the fixture halves 122a, 122b areinterconnected via a pivot pin 124, which allows them to rotate relativeto one another. Each of the fixture halves 122a, 122b includescorresponding positioning indicia 127 which enables them to bepositioned at a desired angle, such as the obtuse angles illustrated inFIG. 7 and 13. Each fixture half 122a, 122b is secured to the trusstable 20 via a secondary locator stop 126 in the same manner describedabove for the fixture 100.

Referring now to FIGS. 14 through 17, the ejector unit 140 includes alifting mechanism 142, a mounting rail 144, and a plurality of ballbearings 146 mounted within mounting shells 148. The lifting mechanism142 is configured to move the mounting rail 144 between a retractedposition (FIG. 14), in which the ball bearings 146 are positioned in thechannel 28 beneath the plane defined by the upper surfaces 52 of suchtable panels 50, and an extended position (FIGS. 15 and 16), in whichthe ball bearings 146 extend above the plane defined by the uppersurfaces 52. Because the ball bearings 146 are free to rotate in anydirection within their mounting shells 148, a truss supported by theball bearings 146 is similarly free to move in any direction when themounting nail 144 is extended. As such, a completed truss can be ejectedfrom either the side or the end of a truss table 20. The liftingmechanism 142 is preferably activated by a pneumatic cylinder (notshown), but can be activated by other means, such as an electric motoror a hydraulic cylinder. Also, other lifting units, such as inflatableair springs or bags, telescoping rods, and the like, can be used withthe present invention.

In addition, alternative ejection units are illustrated in FIG. 15A,which shows a side eject mechanism 150 that includes a plurality ofwheels 152, and FIG. 18, which shows an end eject mechanism 160 thatutilizes an elongate roller 162.

In operation, each truss table 20 is first registered relative to othertruss tables 20 to be employed in constructing a truss. This can beaccomplished by positioning the truss tables 20 so that their channels30 are parallel, then adjusting the magnetic scales 40 within the gaps58 to align with each other (FIG. 3). Aligning can be performed by, forexample, suspending a wire over one end of each truss table 20, thenmoving each of the scales 40 until its "0" mark aligns with the wire.Because the scales 40 include a magnetic lower surface 44 and thechannel floor 32 is ferromagnetic, the scale 40 adheres to the floor 32irrespective of their relative positions. As a result, the adjustment ofthe scales 40 for multiple truss tables 20 can be carried out quicklyand efficiently.

The skilled artisan will also recognize that the scales 40 can beincluded in additional channels 30, or even in all channels 30. Thisconfiguration, once registered as described hereinabove, can provide aprecise two-dimensional grid for the positioning of all locator stops.Such a grid would be particularly useful when employed in conjunctionwith a computer software program for generating locator stop positions.

Next, a desired position for each primary locator stop 60 is selectedfrom a manual drawing or, more preferably, is provided by a trussconstruction software program such as the FREEFORM program noted above.Such a drawing or program should indicate the proper location of thepositioning edge 78 of the slide block 75 relative to the measuringscale 40, which should in turn position the disk 61 at the desiredlocation along the length of the channel 30. At this point the nut 71and bolt 65 are loosened such that the disk 61 and the nut 71 are notclamped tightly to the lateral edge portions 56 of adjacent panels 50.The slide block 75 of the locator stop 60 then slides within the channel30 to the selected position, with the sliding motion halted when thepositioning edge 78 is aligned with the selected location on thepositioning indicia 42 of the scale 40 (FIG. 4). At that point, the bolt65 is tightened so that the disk 61 and nut 71 clamp onto, respectively,the upper surfaces 52 and lower surfaces 54 of adjacent panels 50 (FIG.5). As it clamps against the lower surfaces 54 with its wings 73, thenut 71 rises somewhat from its seated position in the slide block 75 sothat its body 72 is positioned within the gap 58, but a portion of theprojection 74 remains captured within the recess 76. Once the bolt 75 issufficiently tight, the primary locator stop 60 will remain in place astruss planks are positioned against it. Those skilled in this art willrecognize that, although the illustrated configuration of the nut 71 ispreferred, other configurations, such as those in which the body 72 andprojection 74 take different shapes, are also suitable for use with thepresent invention. In particular, the body 72 should be configured sothat at least a portion thereof can fit within the gap 58 and the wings74 should be of sufficient length to bridge the gap 58.

After each of the primary locator stops 60 is in place, the truss plankscan be placed into their proper positions, and the secondary locatorstops 80 can be inserted into channels 30 to abut some or all of thetruss planks. To insert a secondary locator stop 80 within a channel 30,the rotary T-nut 91 is rotated to a position in which the wings 94extend toward opposite ends of the channel 30. In this position, thebody 92 of the nut 91 fits within the gap 58 above the channel 30 andcan therefore be lowered into the channel 30. The locator stop 80 isthen lifted so that the sidewalls 96a, 96b are positioned within the gap58 facing the edges of adjacent panels 50, with the wings 94 bridgingthe gap 58. Rotation of the bolt 85 approximately 45 degrees relative tothe nut 91 causes the nut 91 to rotate until the sidewalls 96a, 96bcontact the edges of the panels 50 and the wings 94 underlie the lowersurfaces 54 of the panels 50. Continued rotation of the bolt 85 elevatesthe nut 91 and thereby causes the disk 81 and the wings 94 to clamp theadjacent panels 50 and thereby secure the secondary locator stop 80thereto. Thus, the secondary locator stop 91 can be inserted into thechannel 30 via the gap 58 rather than having to be inserted through anopen end of the channel 30, which saves a significant amount of timeduring the set-up process.

It is also contemplated that the locator stops 60, 80 can be used inconjunction with a system, such as the "Jet-Set" set-up system producedby Omni, that automatically moves the locator stops 60, 80 to theirdesignated positions in response to data generated by a computersoftware program and implemented via a central controller.

Those skilled in this art will appreciate that, although the illustratedconfiguration of the nut 91 is preferred, other configurations are alsosuitable for use with the present invention. For example, otherconfigurations of the body 92 that enable the nut 91 to be slipped intochannel 30 via the gap 58 rather than through the open end of thechannel 30, yet still prevent rotation of the nut 91 during rotation ofthe bolt 85 (such as a different parallelogramatic shape, a hexagonal oroctagonal shape, or the like) can be used. The wings 94 should, ofcourse, be slender enough to slip through the gap 58 during insertion,but should be of sufficient length to bridge the gap 58 when rotated tounderlie the panel lower surfaces 54.

It is also noteworthy that, in tightening the bolts 65, 85, the operatorcan use a standard ratchet-style wrench designed for hexagonal-headedbolts. This contrasts with the bolts included in prior art locatorstops, which typically were Allen-headed bolts. These bolts presentedproblems in tightening because the standard Allen wrench is ofinsufficient length to provide enough torque to clamp the locator stopsecurely. However, the hexagonal heads of the bolts 65, 85 can betightened with standard hex-head wrenches, which are typically longenough to provide sufficient torque for secure clamping. Also, thecollars 67, 87 increase the surface area over which the clamping forceis applied and thereby improve clamping.

Once the secondary locator stops 80 have been positioned in this manner,semi-permanent fixtures 100 and angled fixtures 120 can also be added tosecure the truss. A fixture 100 can be secured to the truss table 20 byplacing the bearing surface 106 in abutting relationship with a trussplank, then positioning the bolt 85 of a secondary locator stop 108within the slot 105 (FIG. 10). The nut 91 can then be slipped into achannel 30 via a gap 58, and the bolt 85 can be tightened to clamp theinner panels 103 of the capture rails 102 against the upper surfaces 52of adjacent panels 50. Those skilled in this art will appreciate thatthe capture rails 102 should be of sufficient length that they cross agap 58 in which the secondary locator stop can be inserted; it ispreferred that they be at least 6 to 12 inches in length.

Also, if an angled fixture 120 is to be used, it can be secured to thetruss table by inserting locator stops 126 in each of the slots 123 ofthe fixture halves 122a, 122b. The positioning indicia 125 can be usedto pivot the fixture halves 122a, 122b relative to one another to definea desired angle. The fixture halves 122a, 122b are then secured to theupper surfaces 52 of panels 50 with two secondary locator stops 126 inthe manner described hereinabove for the fixture 100 so that side edgesof the fixture halves 122a, 122b abut the edges of truss planks to bejoined (see FIGS. 7 and 13).

It is also of note that, if the nut 91 is fully tapped, and cantherefore continue to receive the bolt 85 as the bolt's lower end passesthrough the lower portion of the aperture 90, the same disks 81, bolts85, and nuts 91 can be employed for both secondary locator stops 80 usedto secure the fixtures 100 and 120 and for those used alone as describedabove.

Once the secondary locator stops 80 and fixtures 100, 120 are secured tothe truss table 20, truss plates are positioned at the joints of thetruss and pressed into the truss planks with a pressure roller. Thecompleted truss is ejected with the ejector unit 140, and a new set oftruss planks is positioned with the primary locator stops 60 and thesecondary locator stops 80 as guides.

During the placement of new truss planks within the pattern defined bythe locator stops 60, 80 and any fixtures 100, 120, on many occasionsthe operator will recognize that some of the planks are warped or bowedto a sufficient degree that the planks fail to fit within the desiredpattern. Because the disks 61, 81 of the locator stops 60, 80 includethe beveled surfaces 63, 83 between their upper surfaces 62, 82 andtheir side walls 69, 89, truss planks that are warped or bowed can beforced into position, as the bevelled surfaces 63, 83 urge the planks totake a position within the pattern as they receive downwardly-directedpressure. The bevelled surfaces 63, 83 also assist in the repositioningof warped truss planks that are forced out of their proper positions bythe pressure roller during construction. The same effect is induced bythe bevelled surface 107 of the bearing insert 106, which also urgesbowed planks to take their positions within the desired pattern.

Once the truss has been formed on the truss table 20, it is ejected withthe ejector unit 140 (FIGS. 14 through 17). The lifting mechanism 142 isactivated by the pneumatic cylinder and causes the mounting rail 144 andthe ball bearings 146 to rise above the plane defined by the panel uppersurfaces 52 (FIG. 15). The mounting rails 144 of all of the truss tables20 are lifted in unison, thereby lifting the truss from the uppersurfaces 52 of all panels 50. Because the ball bearings 146 are free torotate in any direction relative to their respective mounting shells148, the truss can be easily ejected off the side or the end of thetruss table 20 as desired (FIG. 16).

It will be understood by those skilled in this art that, although ballbearings 146 are preferred, other means for ejecting a truss from atruss table can also be used with the present invention. For example, aseries of upright wheels mounted in rotating vertically-orientedspindles can also enable an operator to eject a truss in eitherdirection. Such wheels can include detentes or other means for haltingtheir rotation in a preferred orientation, such that all of the wheelscan be aligned for end ejection or side ejection as desired.

The embodiments illustrated and described above disclose typicalembodiments of the invention and, although specific terms are employed,they are used in a generic and descriptive sense only and not for thepurposes of limitation, the scope of the invention being set forth inthe following claims.

That which is claimed is:
 1. A table for forming trusses, comprising:asupport frame; first and second substantially horizontally-disposedelongate panels, each of said panels having an upper surface, a lowersurface, and opposing lateral edge portions, said panels beingpositioned so that their respective upper surfaces are substantiallycoplanar and so that a first of said lateral edge portions of said firstpanel is in adjacent, non-contacting relationship with a first of saidlateral edge portions of said second panel to form a gap therebetween; afirst channel having a generally horizontal floor and opposed side wallsextending upwardly therefrom, one of said side walls supporting thelower surface of said first panel, and the other of said side wallssupporting said second panel, said floor being supported by said frameand positioned beneath said gap so that said first lateral edge portionof said first panel and said first lateral edge portion of said secondpanel overhang said floor, said floor being formed of a ferromagneticmaterial; and magnetic positioning indicia means located within saidchannel and magnetically attached to said first channel floor.
 2. Thetable defined in claim 1, wherein said magnetic positioning indiciameans comprises a magnetic measuring scale.
 3. A table for formingtrusses, comprising:a support frame; first and second substantiallyhorizontally-disposed elongate panels, each of said panels having anupper surface, a lower surface, and opposing lateral edge portions, saidpanels being positioned so that their respective upper surfaces aresubstantially coplanar and so that a first of said lateral edge portionsof said first panel is in adjacent, non-contacting relationship with afirst of said lateral edge portions of said second panel to form a gaptherebetween; a first channel having a generally horizontal floor andopposed side walls extending upwardly therefrom, one of said side wallssupporting the lower surface of said first panel, and the other of saidside walls supporting said second panel, said floor being supported bysaid frame and positioned beneath said gap so that said first lateraledge portion of said first panel and said first lateral edge portion ofsaid second panel overhang said floor; a first fixture for abutting atruss plank, said first fixture comprising a pair of elongate siderails, each of which includes opposed ends, a cross member attached toone of said ends of each of said pair of rails such that an open-endedelongate slot is defined by said cross member and said rails, and abearing surface for abutting a truss plank, said first fixture restingatop one of said first and second panels with said rails being generallyhorizontally disposed and a portion of said slot overlying a portion ofsaid first channel; and a securing unit that extends through said slotinto said channel for securing said fixture to said table in positionfor said fixture bearing surface to abut a truss plank.
 4. The trusstable defined in claim 3, wherein said fixture bearing surface isreleasably secured to said fixture cross member.
 5. The truss tabledefined in claim 3, wherein said fixture bearing surface merges with abevelled surface position above said bearing surface.
 6. The truss tabledefined in claim 3, wherein said securing unit includes a disk thatoverlies said fixture rails, a retaining nut that is positioned withinsaid channel, and a bolt that extends through an aperture in said diskand is threadedly received in said retaining nut.
 7. The truss tabledefined in claim 6, wherein said retaining nut and said slot are sizedand configured such that, when said retaining nut is in a first rotativeorientation, said nut is sufficiently narrow to slip through said slot,and in a second rotative orientation, said nut is sufficiently wide thatit cannot slip through said slot.
 8. A table for forming trusses,comprising:a support frame; first, second and third substantiallyhorizontally-disposed elongate panels, each of said panels having anupper surface, a lower surface, and opposing lateral edge portions, saidpanels being positioned such that their respective upper surfaces aresubstantially coplanar and so that a first of said lateral edge portionsof said first panel is in adjacent, non-contacting relationship with afirst of said lateral edge portions of said second panel to form a gaptherebetween, and a second of said lateral edge portions of said secondpanel is in adjacent, non-contacting relationship with a first of saidlateral edge portions of said third panel to form a second gaptherebetween; first and second channels, each of which has a generallyhorizontal floor and opposed side walls extending upwardly therefrom,one of said side walls of said first channel supporting the lowersurface of said first panel, and the other of said side walls of saidfirst channel supporting said second panel, one of said side walls ofsecond channel supporting the lower surface of said second panel, andthe other of said side walls of said second channel supporting saidthird panel, said floors being supported by said frame and positionedbeneath one of said gaps so that said first lateral edge portion of saidfirst panel and said first lateral edge portion of said second paneloverhang said floor of said first channel and said second lateral edgeportion of said second panel and said first lateral edge portion of saidthird panel overhang said floor of said second first channel; a pivotingfixture for abutting a pair of adjacent truss planks, said pivotingfixture comprising two halves, each of which comprises a pair ofelongate side rails and a cross member, wherein said cross member isattached to one ends of each of said pair of rails such that anopen-ended elongate slot is defined by said cross member and said rails,said pivoting fixture resting atop at least one of said first, secondand third panels with said rails being generally horizontally disposedand a portion of each of said slots overlying a portion of at least oneof said first and second channels, said cross members of said fixturehalves being pivotally interconnected; and first and second securingunits, each of which that extends through a respective slot of a fixturehalf into an underlying first or second channel for securing saidpivoting fixture to said table so that one of said rails from eachfixture half defines a truss angle with one of said rail from the otherfixture half, thereby providing an angled guide for positioning trussplanks.
 9. The truss table defined in claim 8, wherein said pivotingfixture further comprises positioning indicia on said fixture halves toindicate the magnitude of the truss angle.